Simplified hydraulic actuating mechanism



M. L. CRIPE May 1, 1962 SIMPLIFIED HYDRAULIC ACTUATING MECHANISM Filed Nov. 16, 1959 INVENTOR. MAXWELL L.- CR/PE 4: I hat d a unit we Fntentetl May 1, tear.

abut the rear flange of t e spool shaped poppet member 3,031,851 36 toclose off the vacuum valve port 34; and continued EIMPLEFED gggigzfg forward movement of the diaphragm 31 thereafter lifts Maxwell L. Cripe, South Bend, Ind, assignor to The Bendix Corporation, a corporation of Delaware Filed Nov. 16, 1959, Ser. No. 853,268 4 Claims. (Cl. 60-54.6)

The present invention relates, as indicated, to a new and improved hydraulic actuating mechanism for valves and the like; and more particularly to a simplified reaction producing sealing structure for such use.

An object of the present invention is the provision of a new and improved simplified design of sealing structure for small diameter bores which can be easily installed and which does not tilt out of sealing engagement with its cooperating cylinder walls.

The invention resides in certain constructions and combinations and arrangements of parts; and further objects and advantages of the invention will become apparent to those skilled in the art to which the invention relates from the following description of the preferred embodiment described with reference to the accompanying drawing forming a part of this specification, and in which:

The solitary FIGURE of the drawing is a cross sectional view of a power operated fluid pressure intensifying unit for actuating automotive braking systems and the like, and which embodies principles of the present invention.

The fluid pressure intensifying unit shown in the drawing is of the general type shown and described in the Pfeifer Patent No. 2,867,090; and for a complete understanding of its construction and operation, reference may be had to that patent. In order that the present invention can be understood without referring to that patent, a short general description of its principal parts and their operation will now be given.

The fluid pressure intensifying unit shown in the draw ing generally comprises a hydraulic chamber A having a movable wall or piston B therein which is stroked by a power piston or movable wall C through the interconnecting piston or thrust rod D. Fluid pressure from the manually actuated master cylinder (not shown) of a vehicles braking system is communicated to the inlet connection it), and thence flows to the follow-up chamber 12 which lies on the back or left hand side of the hydraulic piston B. Fluid pressure from the follow-up chamber 12 is also communicated by means of a passageway 14 to a hydraulic actuating chamber 16, the pressure in which is used to actuate the pneumatic control valve structure E which controls the operation of the power piston C.

The control valve E is generally formed by means of a vacuum valve chamber 18, a control'chamber 2i and an atmospheric chamber 22 spaced apart in that order, forwardly of the hydraulic actuating cylinder 16. Vacuum is continually communicated to the front power chamber 24 on the front side of the power piston C; and from thence it flows through a suitable passageway 26 to the vacuum valve chamber 18. The atmospheric valve chamber 22 is separated from the control chamber 20 by means of a cast partition member 28 having an atmosphericvalve port 30 therein; and the vacuum chamber 18 is separated from the control chamber 20 by means of a flexible'diaphragm having a' centrally located annular stiffening ring 32-the center opening 34 of which forms the vacuum valve port of the valve. Atmospheric and vacuum valve ports 30 and 34 are adapted to be closed oft" by means of a spool shaped poppet member 36-the opposite end flanges of which are positioned forwardly of the respective seats 30 and 34, and the interconnecting stem portion 38 of which extends through the atmospheric valve port 30. It will be seen that forward movement of the flexible diaphragm 31 causes the stiffening ring 32 to the forward flange of the spool shaped poppet member 36 out of engagement with the partition 28 to open the atmospheric valve port 30. Atmospheric pressure is thereby permitted to flow into the control chamber 20 and hence through a conduit 42 to the power chamber 54 on the rear side of the power piston C to drive the movable wall B forwardly thereby to displace fluid from the hydraulic chamber A. The flexible diaphragm struc ture 31 is normally held reaiwardly out of engagement with the spool shaped poppet member 36 by means of a valve return spring 46; and it will therefore be seen that the force of the valve return spring 46 must be overcome by hydraulic actuating pressure in the hydraulic actuating cylinder =16.

. There are three general types of sealing structures used to hold hydraulic pressure: O-rings, U-packings, and cupshaped seals. The design of the fluid pressure intensifying units with which we are concerned is generally such that the hydraulic actuating cylinder 16 has a diameter in the range of from approximately to /2 inch. As will be seen by referring to the previously mentioned Pfeifer Patent No. 2,867,090, U-packings must be seated into recesses in the outer periphery of a piston structure; and in order to get them into position, they must be stretched over the full diameter of the piston before they can be seated into their receiving grooves. As the nominal diameter of the seal becomes smaller, it is generally true that the seals must be stretched a larger and larger percentage of its nominal diameter during its installation in the receiving groove; and as a practical matter seals of /2 inch nominal diameter turn out to be the smallest diameter seal which can be installed in this manner. With seals smaller than /2 inch, it is necessary that the seal receiving groove be formed by piston sections which separate; and it is therefore an object of the invention to provide a sealing structure for single piece pistons which can be used for diameters below approximately V2 inch.

O-ring type of seals are subject generally to the same type of difficulties enumerated above for the 'U-packings; Cup-shaped seals are usually installed against the end face of a piston which has a close sliding fit in the cylinder chamber, and it is necessary to provide a hold-down spring or the like to constantly bias and hold the cup seal against the face of the piston in order that the cup shaped seal does not become cocked in the bore and thereby forced out of sealing engagement with the sidewalls of the cylinder. In order to use a. cup-shaped seal in the cylinder chamber 16, therefore, it would be necessary to install a coilspring between the left hand end of the chamber 16 and the cup-shaped seal to hold the seal in position. It is desired in the type of unit shown in the creased, higher actuating pressures must be produced in the actuating chamber 16 in order to bring the unit into operation. According to principles of the present invention, therefore, it is desired to provide a new and improved sealing structure which can be used in small diameter bores, and which does not require a hold-down spring in order to hold the seal in position.

According to principles of the present invention, the

hydraulic actuating cylinder 16 is formed by means of a stepped bore having a small diameter portion and a large diameter portion separated by a shoulder 48. A rubber plug 54 having a large diameter bore portion which substantially fills the bore and a small diameter portion which substantially fills the small diameter bore 48 is positioned in the chamber 16 adjacent the shoulder 52. The small diameter portion of the rubber plug 54 is provided with an annular lip edge 56 so that hydraulic pressure exerted thereagainst forces the lip into sealing engagement with the sidewalls of the chamber 16.

The small diameter portion and large diameter portion of the plug 54 are of course integral; and the large diameter or flange portion has the function of holding and supporting the small diameter portion in the bore 16 in such manner that the annular lip edge 56 is not tilted out of engagement with the sidewalls of the chamber 16. The large diameter flange portion of the plug 54 will normally be held in engagement with the shoulder 52 by means of an annular hold-down ring, which in the embodiment shown in the drawing is formed in two sections. The hold-down ring shown in the drawing includes a first or large diameter ring 60 held in position by the snap ring 62 and further includes a second ring or flanged bushing 6ithe small diameter portion of which extends through the central opening of the first ring 60 into engagement with the plug 54 and the flanged portion of which is held in position by the snap ring d6. The flanged bushing 64 has an axially located opening therein which forms a piston chamber 68; and the structure is completed by a flanged piston 70, the small diameter section of which is received in the piston chamber 68 and the end of which is in abutment with the plug 54. The flanged portion of the piston '74 serves as an abutment for the snap ring 72 which prevents the piston 74 from being blown out of the chamber 68 by the rubber plug 54. Movement of the piston 70 is transmitted to the stiffening ring 32 0f the valve structure by means of the pin 74 and spider arrangement 76.

Operation of the valve actuating structure above described is initiated when pressure is admitted to the chamber 16; whereupon the annular lip edge 56 is forced into sealing engagement with the sidewalls of the chamber 48 and thereby exerts pressure on the rubber plug 54. The opposite face of the rubber plug 54 is generally confined by the rings 60 nad 6d and the end face of the piston 70; so that the hydraulic pressure exerted upon the plug 54 produces a deformation pressure of the confined plug. Deformation of the plug 54 is, of course,

exerted against the end of the piston 79, and the rubber plug 54 flows into the piston chamber 68 to move the piston 70 forwardly and thereby actuate the valve struc ture E. It will be seen that a portion of the rubber plug 54 is always confined between the shoulder 52 and the hold-down rings 60 and 64 to hold the small diameter portion of the plug from tilting in the small diameter bore 48, and that it thereby holds the annular lip edge 56 into sealing engagement with the sidewalls of the bore 48. By means of this construction, there is no lower limit to the diameter of the seals which can be made.

While the invention has been described in considerable detail, I do not wish to be limited to the particular constructions shown and described; and it is my intention to cover hereby all novel adaptations, modifications and arrangements thereof which come within the practice of those skilled in the art to which the invention relates and which come within the scope of the following claims.

I claim:

1. A simplified hydraulic actuating mechanism for valves and the like comprising: a housing member having an axially extending stepped chamber with generally concentric small and large diameter portions with a shoulder at their juncture, a plug of rubber-like material having a large diameter portion substantially filling said large diameter portion of said chamber and an integral small diameter boss on one face of said plug substantially filling said small diameter portion of said chamber, the end of said boss including an annular lip on its outer edge for sealing engagement with the sidewalls of said small diameter portion of said chamber, said large diameter portion of said plug supporting and holding said small diameter portion in sealing engagement with the sidewalls of said small diameter portion of said chamber, and force transmitting means positioned against the opposite face of said plug in said large diameter portion of said chamber for transmitting force to and from said plug.

2. A simplified hydraulic actuating mechanism for valves and the like comprising: a housing member having an axially extending stepped chamber with generally concentric small and large diameter portions with a shoulder at their juncture, a plug of rubber-like material having a large diameter portion substantially filling said large diameter portion of said chamber and an integral small diameter boss on one face of said plug substantially filling said small diameter portion of said chamber, the end of said boss including an annular lip on its outer edge for sealing engagement with the sidewalls of said small diameter portion of said chamber, an annular retainer positioned against the outer peripheral face of said plug in said large diameter portion of said chamber, said retainer having an axially extending cylinder chamber therein, and a piston positioned in said cylinder chamber for abutment with said plug.

3. A simplified hydraulic actuating mechanism for valves and the like comprising: a housing member having an axially extending stepped chamber with generally concentric small and large diameter portions with a shoulder at their juncture, a plug of rubber-like material having a large diameter portion substantially filling said large diameter portion of said chamber and an integral small diameter boss on one face of said plug substantially filling said small diameter portion of said chamber, the end of said boss including an annular lip on its outer edge for sealing engagement with the sidewalls of said small diameter portion of said chamber, a first annular retainer washer in said large diameter portion of said chamber adjacent the face of said plug, a second annular retainer washer in said chamber extending into the central opening of said first washer for abutment with said plug, said second washer having an axially extending cylinder chamber therein, means for retaining said washers in said chamber, and a piston positioned in said cylinder chamber for abutment with said plug.

4. A simplified hydraulic actuating mechanism for valves and the like comprising: a housing member having an axially extending stepped chamber with generally concentric small and large diameter portions with a shoulder at their juncture, a plug of a fiowable elastomeric material having a larger diameter portion substantially filling said large diameter portion of said chamber and an integral small diameter boss on one side of said plug extending into said smaller diameter portion of said chamber, at least a portion of said boss having an interference fit with the sidewalls of said small diameter portion of said chamber to form a seal therewith, said large diameter portion of said plug supporting and holding said small diameter portion in sealing engagement with the sidewalls of said small diameter portion of said chamber, and means for transmitting force'against the opposite side of said plug in said large diameter portion of said chamber.

References fitted in the file of this patent UNITED STATES PATENTS 

